Low speed servo control for single Gimbal control moment gyros using back-stepping time-varying sliding model control

Single Gimbal Control moment gyroscope(SGCMG) is a typical servo system application and has a broad prospect in spacecraft attitude adjustment. In order to optimize the performance of SGCMG outer frame servo system on smooth speed, position tracking and robustness, a nonlinear servo control algorithm for the permanent-magnet synchronous motor(PMSM) system using back-stepping adaptive switch gain time-varying sliding mode control(SMC) is designed in this paper. First, a time-varying SMC approach based on back-stepping and adaptive switch gain is presented. The time-varying sliding mode controller refresh the slide surface, and the switch gain of controller is adaptively changed. Then, a SMC disturbance observer is proposed to reduce the impact of load torque and coefficient disturbance on the control system. Simulation results show the validity of the proposed control method.